The structure of an aircraft includes stringers that serve as stiffeners for structural reinforcement of wing panels. Some stringers, known as vent stringers, are configured not only for structural reinforcement but also for venting fuel tanks in the wing. Vent stringers may terminate between the outboard and center wings.
Vent stringers may be interrupted along their lengths by other structural members oriented transversely to the vent stringers. In such cases the vent stringers have open ends beside such transverse structural members, and are equipped with fittings that close the vein stringer but include a passage that continues the vent flow path onward from the open ends. The passage of such a fitting may be configured to connect a vent stringer with a vent opening that passes through a transverse structural member, or with a vent tube that bypasses the transverse structural member.
Current fittings at side-of-body (SOB) are complex in design, difficult to seal and time-consuming to assemble. Such fittings cannot be fully installed until after wing-to-body join when fasteners have been installed through the skin panel and splice strap. These fittings have multiple pieces that provide a path for the fuel vent system when sealed, but prevent access to the wing-to-body join fasteners without disassembling the fitting. Sealing part of the fuel vent system during wing-to-body join requires sealant to cure before leak tests can be performed and wing, fuel tank closed, resulting in long assembly flow hi other current applications, separate fuel vent system bypass fittings located outboard of the SOB are mechanically fastened to the stringer and require cutting an opening in the cap of the stringer and a corresponding increase in wing skin and stringer size locally to compensate for the opening. This results in a location well outboard of the SOB area and a long length of vent tubing required. It also requires sealing installation fasteners and a fuel (seal) data within the stringer that are difficult to access.
Accordingly, there is a need for a fitting design that is reliable, inexpensive to fabricate, and can be installed with a minimum of alteration to adjacent aircraft structure.